Written by Ada’s Medical Knowledge Team
What is syphilis?
Venereal syphilis, commonly known as simply “syphilis”, is an infection caused by the bacteria Treponema pallidum (subspecies pallidum). Syphilis is spread by direct contact with an infected individual, such as:
- Sexual contact
- From mother to fetus in utero
- Via blood transfusions
- Contact with a syphilis sore in a non-genital region (although this is rare)
- Needle sharing amongst injecting drug users
It can be spread by any sexual activity, making it a sexually transmitted infection (STI). Syphilis can be spread by oral sex, anal sex and vaginal sex, as well as any other genital contact and sharing of sex toys. Sharing food and drinks, towels and toilet seats with people who have syphilis is considered safe, as is hugging, holding hands, coughing and sneezing. It is possible for syphilis to be spread by kissing, if the infected individual has a syphilis sore in the mouth, however this is rare.
It is also possible for mothers to transmit syphilis to their babies in utero. This is known as congenital syphilis.
Other treponemal diseases caused by Treponema pallidum are related to syphilis but are not spread by sexual contact. These include yaws (caused by subspecies pertenue), bejel (subspecies endemicum) and pinta (caused by subspecies carateum) which all affect the skin or bones.
Syphilis used to be much more common than it is today, but after the introduction of treatment with the antibiotic penicillin after World War Two, the number of people with syphilis dropped globally. However, since the beginning of the twenty-first century, the incidence (how many people are newly reported as having syphilis) is rising in the West, mostly due to unsafe sexual practices. Currently, there are about 10.6 million cases of syphilis worldwide.
Syphilis is a concern among all groups, as it is a major risk factor for passing on HIV. The incidence of syphilis is rising most sharply among men who have sex with men (MSM): between 2015 and 2016, the reported number of cases of syphilis rose 18% in the UK, and more than half of these cases were among men who have sex with men. In the USA, according to the Centers for Disease Control, approximately half of men who have sex with men who have syphilis are also HIV-positive, and men who are HIV-negative but do have syphilis are more likely to contract HIV in the future. This is generally believed to be the result of higher rates of unprotected sexual practice in this group, rather than the type of sexual activity itself. Unprotected sexual contact is inadvisable regardless of sexual orientation.
The stages of syphilis
Syphilis has four stages:
Primary syphilis is the initial stage of infection, in which a flat, painless ulcer develops at the site of infection. This ulcer is called a chancre.  It usually appears between 10 and 90 days after contact with an infected individual, and heals on its own after two to twelve weeks (although the affected person remains infectious). .
Secondary syphilis follows two to ten weeks after primary syphilis. It has many symptoms, including a distinctive rash. The rash is usually at its worst between three and four months after infection. This phase can last between one and six months.
Latent syphilis, early and late. In early latent syphilis, the infected person is asymptomatic (has no symptoms) but is still infectious. In late latent syphilis, the person is less infectious. The latent phase may last for up to 25 years in some cases, although not all individuals will have a latent stage.
Tertiary syphilis can occur from 3 to 15 years after the initial infection, and is when the affected individual develops complications from long term infection. The complications can include severe neurological and cardiovascular effects. In this stage soft, rounded tumor-like areas of inflammation called gummas can also appear.
Secondary syphilis appears only after the symptoms of primary syphilis have passed, usually around two to ten weeks after the primary chancre has appeared. About one in four people who have untreated primary syphilis will develop secondary syphilis.
In secondary syphilis, the affected person experiences a generalized infection. This secondary phase, if left untreated, lasts for up to six months, with symptoms recurring during that period. Without treatment, the symptoms will, in most cases, resolve spontaneously, but the infected person will then progress into the latent or tertiary phase of the disease.
Symptoms of secondary syphilis
Secondary syphilis is a generalized infection affecting the entire body, so it has a number of possible symptoms. People with syphilis may show some or all of these. Common symptoms include:
- A painless, non-itchy rash, which is generally bilaterally symmetrical (the same on both sides)
- Swollen lymph nodes in the neck, armpits and groin
- Malaise, aches and pains
- A mild fever
- Loss of appetite
- Sore throat
- Neck stiffness
- A red or pink skin rash, turning reddish-brown. This rash may be very faint. It can occur on the soles of the feet, the palms of the hands, and on the face. In some cases this rash may spread to cover the entire body. It is generally not itchy.
- Flat, soft growths around moist, warm areas of the body, such as the vagina and anus. These are known as condylomata lata and are sometimes confused with genital warts. They may be pink or grey. These growths are not painful or itchy, and often disappear spontaneously. They may also occur on other mucus membranes.
- White patches on the roof of the mouth and the tongue.
- Weight loss
- Patchy alopecia (hair loss)
- Kidney problems (such as glomerulonephritis)
- Splenomegaly (an enlarged spleen)
- Cranial nerve palsies (weakness or paralysis of nerves in the head and face. These can cause various problems, for example, double vision)
- Periostitis (inflammation of membranes around bones)
- Anterior uveitis (inflammation inside the middle layer of the eye)
Diagnosing secondary syphilis
The process of diagnosing secondary syphilis will typically include taking the person’s medical history to assess whether they have been at risk of infection, as well as examining any physical symptoms they are showing. However, laboratory tests are the only way to be sure whether or not a person has acquired the infection. Situations in which tests are especially necessary include:
- If the affected person thinks they may have symptoms
- If they have recently had unprotected sex with a new partner
- If they or their partner have had unprotected sex with other partners
- If they have another STI, for example gonorrhea or chlamydia
- If they are HIV-positive.
- If their partner has disclosed that they have an STI
- If they are pregnant or planning to become pregnant
- If the affected person is a man who has sex with men
- If they have previously had syphilis
It is important to test as soon as possible. However as syphilis does not always show up in results if the infection is very recent, re-testing at a later date may be necessary. Even people who are asymptomatic should be tested if they have been at high risk of having acquired or passed on syphilis. Infected people should also be tested for HIV, and ideally a full STI panel, where tests are done for a range of STIs, should be ordered as well.
Tests for syphilis
There are a number of laboratory tests for syphilis. The diagnosis of syphilis is usually made by taking a blood test to screen for the disease, followed by another test or tests to confirm its presence. Tests are done on blood as well as body fluids. The most important screening tests are:
- Venereal disease laboratory test (VDRL) including an Immunoglobulin M (IgM) test
- Treponema pallidum hemagglutination assay (TPHA)
- Treponema pallidum particle agglutination assay (TPPA)
To confirm the presence of syphilis, a fluorescent treponemal antibody absorbed test (FTA-abs) may be administered. This test, and the tests listed above, all work by detecting antibodies - particles produced by the body’s immune system in response to syphilis infection. The exact tests used and the order they are used in depends on the laboratory.
Self-test kits are available, but are not very accurate. It is advisable to seek assistance from a sexual health clinic, hospital or doctor’s office.
Treatment of secondary syphilis
Syphilis is easily treated using the antibiotic penicillin. Primary, secondary and latent syphilis can all be treated with penicillin, but it is most effective in the primary and secondary phases. Latent syphilis infection can be cured by penicillin, but any organ damage already sustained from longterm infection cannot be undone The same is true of tertiary syphilis.
In patients who are allergic to penicillin, doxycycline and ceftriaxone may be used. Because of increasing antibiotic resistance, azithromycin is no longer very effective.
Treatment does not prevent future re-infection. It is very important that people receiving treatment for syphilis adhere to their treatment regime and abstain from unprotected sexual activity.
When treating syphilis, most physicians prefer to use parenteral (administered by injection) treatment rather than oral treatment, as injecting medication tends to happen under medical supervision, which may mean that the patient has a better chance of adhering to the treatment regime.
The first line of treatment for syphilis is an intramuscular (into the muscle) injection of a single dose of of benzathine penicillin. An alternative treatment is Doxycycline, for patients who are allergic to penicillin.
Improvement is experienced shortly after treatment begins, but the time to complete recovery varies according to how long the infection has been present. Follow-up blood tests are required to check if the treatment has been effective.
Between half and three-quarters of people being treated with antibiotics for syphilis have an unpleasant set of short-term symptoms known as the Jarisch-Herxheimer reaction, which occurs several hours after beginning treatment. As the treponemal bacteria die they release inflammatory substances, and these are responsible for the body’s reaction.  Symptoms can include fever, muscle pain, headache and rapid heartbeat.
People suffering from this reaction can take aspirin or ibuprofen, and should not be left alone in case complications develop, such as panic attacks, faintness, etc. If complications do develop, seek medical help.The condition usually passes within 24 hours, and it not usually considered to be dangerous.
Preventing secondary syphilis
Using a condom can significantly reduce the risk of passing on or catching syphilis from a sexual partner. Since the bacteria responsible for syphilis are transferred through skin abrasions or infected mucous membranes, barrier protection is an effective method of preventing transmission. In primary syphilis, it is important to cover the chancre (the small, painless genital ulcer) with a condom or dental dam if engaging in sexual activity. Additionally, users of intravenous drugs should not share needles.
Secondary syphilis FAQs
Q: Can one contract syphilis from sharing sex toys?
A: Yes. If one’s sexual partner has syphilis and they share sex toys, one may contract syphilis. The risk of this can be reduced by using condoms on sex toys, with a new condom for each partner, and cleaning the toys thoroughly between uses, using soap and water or a dedicated toy cleaning solution. Using the correct type of lubricant is important to toy hygiene, as using the incorrect type will cause damage to the toy’s surface, making it more difficult to clean. Manufacturers usually advise about the correct cleaning and lubrication procedures for their toys.
Q: Should people who are asymptomatic but suspect they may have syphilis seek testing?
A: If you think you have been exposed to syphilis through a sexual or intimate partner, but do not have symptoms, it is highly recommended that you are tested. Some people with syphilis show no symptoms, and their infection is only discovered during routine STI screening. Testing is important if you might fall pregnant, or have multiple sexual partners.
Q: Can I have secondary syphilis without having had primary syphilis?
A: No. The infection is sequential, so everyone with secondary syphilis has had primary syphilis, although it may have been asymptomatic. However, if you seek treatment for secondary syphilis and the treatment is successful, you will not develop latent or tertiary syphilis unless you contract syphilis again.
Other names for secondary syphilis
- Lues secondary state
- Secondary lues venerea
- Secondary syphilis infection
Centers for Disease Control and Prevention. “Syphilis & MSM (Men Who Have Sex With Men) - CDC Fact Sheet.”. 26 September 2017. Accessed 19 March 2018. ↩ ↩
UpToDate. “Syphilis: Epidemiology, pathophysiology, and clinical manifestations in HIV-uninfected patients.”. Accessed 10 April 2018. ↩